Wow that is quite long.
One comment:
In stead of this:
my @sLart; #Assembly for the elements of the email
my @aoaCheck; #Array of checkbox data
#[][0] is the checkbox itself
#[][1] is the 'ticked' variable
#[][2] is the text
my $nLandings = 0; #Number of landing points analysed
my $sServer; #Whois server
my %hoaBank; #Hash of Arrays of banks
my $sBank; #Selected bank from combobox
my $sTo; #Email address of $sBank
my $sFrom; #Spamgourmet prefix for $sBank
it is usually better to declare your variables where you use them first (that way, and with strict, you get a nice warning when you double-use a variable name).